The present invention relates to the preparation of unsaturated fatty acid calcium salt nutritional supplements from high glyceride content polyunsaturated oils, including fish oils. The present invention particularly relates to fatty acid calcium salts rich in desirable unsaturated fatty acids such as omega-3 fatty acids, including eicosapentaenoic acid (EPA), docosahexaenoic acid (DHA), decosopentaenoic acid (DPA) and linolenic acid (LNA).
A variety of unsaturated fatty acids have been identified as desirable for producing a diversity of nutritional and physiological benefits in humans and lower animals, including pets and livestock, and accordingly have attracted attention as nutritional supplements. Omega-3 fatty acids, for example, have been discovered to promote animal fertility, and have other nutritional and physiological properties as well. Conjugated Linoleic Acids (CLA's) have been discovered to possess a diverse and complex level of biological activity. Anti-carcinogenic properties have been well documented, as well as stimulation of the immune system. U.S. Pat. No. 5,914,346 discloses the use of CLA's to enhance natural killer lymphocyte function. U.S. Pat. No. 5,430,066 describes the effect of CLA's in preventing weight loss and anorexia by immune system stimulation.
CLA's have also been found to exert a profound generalized effect on body composition, in particular, upon redirecting the partitioning of fat and lean tissue mass. U.S. Pat. Nos. 5,554,646 and 6,020,378 disclose the use of CLA's for reducing body fat and increasing lean body mass. U.S. Pat. No. 5,814,663 discloses the use of CLA's to maintain an existing level of body fat or body weight in humans. U.S. Pat. No. 6,034,132 discloses the use of CLA's to reduce body weight and treat obesity in humans. CLA's are also disclosed by U.S. Pat. No. 5,804,210 to maintain or enhance bone mineral content.
It is also known that supplementing the diet of livestock with unsaturated fatty acids will alter the livestock fatty acid profile, so that, for example, feeding dairy cows and beef cattle a source of unsaturated fatty acids beneficial to humans will yield dairy and beef products for human consumption enriched with the beneficial unsaturated fatty acids. For example, U.S. Pat. No. 5,143,737 discloses that the unsaturated fat content of milk and meat from ruminant animals can be increased by incorporating the intended unsaturated fat into the diet of the ruminant.
Thus, meat and milk enriched with CLA's and other unsaturated fatty acids can be obtained by supplementing ruminant diets with unsaturated fatty acids such as CLA. Dairy cows and beef cattle fed a source of CLA not only will produce lower fat content dairy and beef products, the products will be enriched with CLA's as well. Dietary supplementation of dairy cows and beef cattle with unsaturated fatty acids beneficial to humans can also be used to displace and thereby reduce the levels of undesirable saturated fatty acids in dairy and beef products.
The beneficial effects produced by unsaturated fatty acids are not limited to CLA's. Other unsaturated fatty acids are disclosed to be useful for treating diabetes (U.S. Pat. No. 4,472,432), heart disease (U.S. Pat. Nos. 4,495,201; 5,541,225 and 5,859,055), prostaglandin deficiencies (U.S. Pat. No. 5,043,328), malaria (U.S. Pat. No. 5,604,258), osteoporosis (U.S. Pat. Nos. 5,618,558 and 5,888,541), cancer (U.S. Pat. No. 5,763,484), immune system function (U.S. Pat. No. 5,767,156), Huntington's Chorea (U.S. Pat. No. 5,837,731) and inflammation (U.S. Pat. No. 5,861,433). The disclosures of the foregoing patents are all incorporated by reference.
It has further been discovered that ruminants fed a source of trans-C18:1 fatty acids will have decreased concentrations of milk fat, hepatic triacylglycerol, and lower incidence of sub-clinical ketosis during early postpartum, and that feeding a source of linoleic (C18:2) fatty acids during the transition period will increase synthesis of PGF2α, The linoleic fatty acids thus hasten uterine involution and reduce the incidence of clinical and sub-clinical uterine inflammation; which translates to increased fertility.
Unsaturated fatty acids, however, undergo hydrogenation to more saturated and completely saturated fatty acids by microbial action in the rumen and must be fed to ruminants in a protected form. The aforementioned U.S. Pat. No. 5,143,737 discloses the encapsulation of unsaturated fatty acids with non-toxic organic materials to protect the unsaturated fatty acids from microbial action in the rumen. The most familiar form in which fatty acids in general are protected from microbial action in the rumen are the fatty acid calcium salts disclosed by U.S. Pat. Nos. 4,642,317; 4,826,694; 4,853,233 and 4,909,138. This form of fatty acid protection is widely accepted in the dairy and beef cattle industries.
Unsaturated fatty acids, however, do not readily react to form calcium salts using the processes disclosed by the above-listed patents. Instead of forming free-flowing granules, a mass develops that hardens into a tough material that resists grinding into the fine particles required for consumption by cattle. The resulting material also lacks storage stability. The product tends to auto-oxidize through an exothermic reaction that leads to a congealing of the product mass from its free flowing granular state to a hard amorphous state, suggesting that significant quantities of unreacted starting materials are present in the final product.
U.S. Pat. No. 6,559,324 discloses hydrolysis methods for the preparation of calcium salts of unsaturated fatty acids having 20 percent by weight glycerides. U.S. Pat. No. 6,576,667 discloses methods by which calcium salts of unsaturated fatty acids having as high as 60 percent by weight glycerides can be prepared. The disclosures of both patents are incorporated by reference. However, commercial sources of unsaturated fatty acids such as fish oils have glyceride contents as high as 100 percent by weight, which remain difficult to convert to storage stable free-flowing fatty acid calcium salts. U.S. Pat. No. 6,576,667 addresses this problem by diluting the high glyceride content oils to glyceride levels below 60 weight percent with lower glyceride content fatty acid feedstocks such as Palm Fatty Acid Distillates (PFAD's). However, this also reduces the unsaturated fatty acid concentration in the fatty acid calcium salt product, requiring greater quantities to be fed as part of a feed ration to adequately supplement the ruminant diet.
U.S. Pat. No. 6,229,031 discloses a saponification method by which calcium salts of fatty acids having as high as 100 percent by weight glycerides can be prepared. The disclosure of this patent is also incorporated by reference. However, calcium salts prepared from fatty acids with a significant degree of unsaturation have been discovered to lack storage stability.
A need exists for a method by which unsaturated fatty acid calcium salts having acceptable storage stability can be prepared.